The American Bankers Association provides an online tool for bank customers to look up the routing number of any participating bank or credit union in the United States. Most banks and credit unions also post their routing numbers prominently on their websites.
Routing numbers are printed on all checks issued by a bank or credit union. The number is printed on the check in two different places and in two different ways. In the upper right area of the check, near the check's sequential number, the routing number is printed in regular ink and in fraction form. The routing number is also on the bottom of the check in its machine-readable, magnetic ink form.